Application Security Groups (ASG) support for App Service Environments (ASE)
As stated in the comments section of this page https://azure.microsoft.com/en-us/blog/applicationsecuritygroups/
"It's on the roadmap, all services integrated with VNet like ASE and SQL MI will be part of ASGs groups, as of today the scope doesn't cover subnets for those services, we are exploring options in the near future."
I am also looking for a similar solution with ASG which protects my Azure PaaS services like App Service, Functions. Only accessible from specific network.